Method of making calcium carbid.



No. 683,962, Patented Oct. 8, I90I. H. MAXIM. mamon or uma cALcluncAnslm (Application Med. June 25, 1895.)

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UNITED STATES PATENT OFFICE.

HUDSON MAXIM, OF NEV YORK, N. Y.

METHOD OF MAKING CALCIUM CARBI.

SPECIFICATION forming part of Letters Patent No. 683,962, dated October8, 190'1.

Application filed June Z5, 1895'. Serial No. 553.952. (No specimens.)

T0 LZ-Z whom, it may concern:

Be it known that I, HUDSON MAXIM, a citizen of the United States,residing at the city of New York, county and State of New York, haveinvented certain new and useful Improvements in Methods of MakingCalcium Carbid, of which the following is a specification.

In practicing my invention I employa revoluble furnace utilizingelectricity as a heating agent and so constructed and so operating underelectrical and centrifugalinuences that great heat energy may bedeveloped and maintained for any desired length of time or continuouslywithout distorting the structure or causing its interior walls tocollapse or run down when subjected to the great heat within. Substancescharged into the furnace may thus be'subjected to a very hightemperature for any required time, most advantageously facilitatingreactions of their fused or volatilized elements. There is embodied inthe furnace a peculiar arrangement of electrodes whereby aprogressively-increasing temperature is produced within the furnacethatis to say, temperature that increases in direction of the general iow ofelectric current through the apparatus. For this purpose I use aninterior common electric conductor adapted to receive independentelectric currents from a series of outer electrodes disposed atsuccessively-advancing points along the furnace, each successive'andadditional heat.

electric current adding quantity to the current already iiowing throughthe interior common electric conductor, whereby is generated an intenseheat, which increases toward the place of discharge of the treatedmaterial. The furnace is provided with an auxiliary interior liningwhich protects its fire-clay or other refractory lining, and also thefurnace body or shell, from injury by This auxiliary protecting-liningmay consist of loose materials thrown into the furnace and distributedand held by centrifugal force against the fire-clay lining as aprotective interior tubular layer of unfused material, or said auxiliarylining may be built up from and be constantly renewed bya portion of thefused lnaterial under treatment, which thus forms a practicallyfrictionless fluid-bed, upon and along which the surplus to enable theinvention to be better under.

stood and not as defining the limits thereof.

Figure l is a longitudinal sectional view of one style of horizontalfurnace apparatus. Fig. 2 is a transverse section thereof, taken on theline Qc in Fig. l.

The numeral l indicates the furnace body or shell, which is preferablymade of steel, and may have a tire-clay or other refractory electricallynon-conductive lining 2, within which is the centrifugally-maintainedauxiliary protective lining or bed 3, hereinafter more fully described.The material et under treatment may be fed from a hopper by a screwconveyer 5 and flows through or along on the bed 3 and discharges at theopposite end into a chute 6, which may convey the treated material toany suitable receiver. Opposite heads 7 8,with interposed insulation 9,of asbestos or other suitable material, are bolted to the ends of thefurnace-body. The head 7 has an opening receiving the materialfeed-spout, and the head 8 has a central opening for discharge of thetreated material and is preferably flared outward and faced byinsulation 10, preferably magnesite. The head S also has a flange 11,which projects inward inside of the fire-clay lining 2 and into theauxiliary protective bed 3 to allow the electric current to be taken offfrom the bed through the head.

The electric appliances furnishing the progressively-increasingtemperature in this apparatus comprise, in connection with the interiorprotective bed 3, a series of outer circumferential electrodes l2,preferably arranged in two opposing radial pairs or in series of four inthe same transverse plane and project-ing inward to the protective bed 3to transmit thereto electric current which usu- IOO ally fuses the bedmaterial to a fluid lsta-te, while it is maintained in tubular form bycentrifugal force. For each transversev or circumferential series ofelectrodes 12, and preferably over an interposed encircling asbestospacking 13, there isshrunk around the steel furnace-body a metal ring orband 13, which for each electrode has a cup-shaped radial projection 14.Inside ofv each cup 14 a shouldered insulation 15 is fitted to thefurnace-body l and its lining 2. The electrode is passed into the cup 14and rests by its shoulder on a shoulderrof the insulation 15. Asuitably-insulated annular packing 16 is placed on the outer end of theelectrode around its outwardly-projecting stem 17, which preferablyenters an opening in a conductive plug 18, screwed into the cup 14 toretain the electrode. Centrifugal force developed by rotation of thefurnace throws the electrode 12 outward and compresses the packing 16between it and the plug to prevent leakage past the electrode of theduid-bed 3 or the fused materials under treatment in the furnace. Theelectrode-retaining plugs 18 of each circumferential series are each incontactwith an independent conductive segment 19 of a ring having asmany segments as there are electrodes in the series, the segments beingpreferably separated by end insulation 20, thus directing the currenttoward the electrodes in contact with the respective segments. The ringmay be removed to allow the plugs to be taken out to give access to theelectrodes and their packings. Each of the uppermost segments 19 in Fig.2 is in circuit by a brush 2l with one pole of a dynamo 22, while thetwo lower segments receive current from separate dynamos 23 throughwires leading to the axis of the antifriction-rollers 24, on which thefurnace rests for rotation at any required speed by one or more pinions25, meshing with a toothed gear 26 on the furnace-body. Wires 27 connecta conductive rod 28 with each of the dynamos 22 23 to receive thereturn-current by means of a brush 29 on the rod bearing on the head 8of the rotating furnace-bod y. There being four currents transmitted toeach circumferential series of electrodes 12, the furnace shown in Figs.1 and 2 and having ve such series will have twenty independent electriccurrents supplied to it, and it may be by as many separate dynamos togive their joint powerful heating effect on the material undertreatment. It will be noticed that by providing the ring 13 withprojecting cups 14 and tting the conductive segments 19 outside of thesecups or the plugs 18 in them considerable space is provided at 30 forcirculation of air inside and quite around the parts 19 to preventoverheating of the exterior contacts by either the electric currentswhich they distribute to the furnace or the heat generated by saidcurrents within the furnace and radiating through its body-wall.

The operation of this apparatus is as follows: Before feeding thematerialA 4 to be treated into the furnace any suitable substance or`compound having'proper electrical resistance and a specific gravityhigher than that of the material to be treated may be charged into therotating furnace upon its lining 2 andV be melted to form the auxiliaryprotective uid bath or bed 3 by dynamos 22 23. The fused material of thebed 3 forms a common interior electrode along which returns theconstantly-increasing electric current derived from the successivecircumferential series of electrodes 12, and whereby a very hightemperature is obtained in the furnace, due mainly to the rapidlyincreasing supply of electric current entering the .duid-A bed towardthe discharge end of the furnace and the resultant heating of the bedincidental to the resistance offered by the bed to the passage of thecommon return-current. The fluid bed is maintained in tubular formagainst the furnace-lining 2 by centrifugal force, which also willmaintain the lining 2v in tubular form against the furnace body or shellshould this lining become softened or partly fused by the intense heatattained within the furnace. As the material 4 is fed into the furnaceby the screw 5 or otherwise, the centrifugal force causes thematerial toassume a tubular form and to ioat or drift forward easily along thetubular fluid-bed 3 while subjected to the intense heat of the electriccurrent derived from the circumferential electrodes 12 and returningthrough the fluid-bed. The electrothermal treatment may continue for alonger or shorter time, as determined by the rapidity of feed of thematerial, or the speed of rotation of the furnace, or the nature of thematerial.- The treated material discharges from the furnace into thereceiver 6. In treating certain classes of materials the fluid-bed 3serves a very important function by constituting a practicallyfrictionless tubular bearing-surface, along and within which the treatedmaterialsare carried, floated, or drifted forward through the furnace bythe developed centrifugal force aided by the natural tendency of thematerials to seek their own level. It will be understood that theHuid-bed 3 may be formed or built up from and be vconstantly renewed bya portion of the materials under treatment, or from one of the productsof the reaction effected in the furnace. One such material is calciumcarbid, to produce which calcium oxid and carbon are fed into thefurnace and subjected to its heat energy. As the reaction takes placeand the carbid is formed, it is carried by centrifugal force against thelining 2 of the furnace-body to form an auxiliary protective liningtherefor, and the surplus carbid will discharge from the furnace intothe receiver 6, the fluid-bed or protective lining being constantlyrenewed by freshly-formed carbid on its way to the outlet. At variousstages of the operation water or other cooling fluid will be thrown loeIrc

over the exterior walls of the furnace from a series of nozzles 60 orequivalent cooling apparatus to prevent overheating of the furnace.These nozzles are shown in Fig. 2 of the drawings.

The apparatus herein described, While of my invention, is not hereinclaimed, as the same will form the subject-matter of anotherapplication.

I claim as my inventionl. The method of making calcium carbid,consisting in maintaining a carbid-conductor incandescent by means of anelectric current, subjecting carbid-forming materials to the heatthereby engendered, thus converting said materials into calcium carbid,maintaining the cross-sectional area of the carbid-conductorapproximately constant by removing the calcium carbid from the furnaceas formed, and supplying fresh materials to the 2o HUDSON MAXIM.

Witnesses:

E. L. Tonn, JAMES HUBER.

